Investigation on Cutting Blasting Efficiency of Hard Rock Tunnels under Different Charge Diameters

Abstract

Considering the low efficiency of cutting blasting in hard rock mine tunnels, a novel solution of increasing the charge diameter of the cutting holes was put forward. To investigate the influence of the charge diameter on the cutting blasting results, three different working conditions of Φ 32 mm, Φ 42 mm, and Φ 50 mm blasting holes combined with Φ 27 mm, Φ 35 mm, and Φ 45 mm cartridges, respectively, were taken as the investigation objects. At first, the theoretical destruction ranges of single cutting holes under the three different charge diameters were computed. The computed results showed that the destruction range of the cutting holes could be expanded by increasing the charge diameter, which would be beneficial to the destruction of the rock far away from the cutting holes in the cutting cavity. Subsequently, numerical simulations of cutting blasting under the three different charge diameters were performed to display the dynamic propagation process of the blasting stress wave. Importantly, the stress field intensity in the cutting cavity was enhanced significantly with the charge diameter. The stronger stress field intensities generated by the larger diameter charges were more conducive to breaking the rock in the cutting cavity into small fragments that were easy to be discarded. Ultimately, a hard rock vertical slope was used instead of the driving face to carry out the cutting blasting experiments, and the hole utilizations of the cutting blasting were 70.4%, 82.0%, and 94.0%, respectively, under the three different charge diameters, from small to large. The experimental results forcefully substantiated that a higher cutting blasting efficiency could be achieved by increasing the charge diameter of cutting holes in hard rock mine tunnels.

Research on the mechanism and application of wedge cutting blasting with hole-inner delay

“…Chen et al 23 carried out numerical analyses and model experiments of wedge cutting blasting under unidirectional pressure and described the adverse effects of unidirectional pressure on damage evolution, cavity volume, and block distribution. Using numerical simulation and full-scale tests, Cheng et al 24 and Gao et al 25 investigated the effect of the charge diameter on hard rock wedge cutting blasting and concluded that increasing the charge diameter could aggravate the breaking degree of the rock mass. In addition to the above studies that have focused on traditional wedge cutting patterns, several recent studies have introduced a hole-outer delay into deep-hole wedge cutting blasting.…”

Study on the law of ore dilution and loss and control strategies under brow line failure in sublevel caving mining

“…In recent years, significant progress has been made in the study of blasting mechanisms with the advancement of physical experiments and numerical simulation techniques [16][17] . Researchers have investigated the mechanisms of rock blasting and fragmentation, as well as the patterns of stress and fracture changes, under different charging structures [18][19] and detonation velocities [20][21][22] .…”